Transactional Composite Applications

Transactional Composite Applications

Frederic Montagut (SAP Labs France, France), Refik Molva (Institut Eurecom, France) and Silvan Tecumseh Golega (Hasso-Plattner-Institut, Germany)
Copyright: © 2009 |Pages: 25
DOI: 10.4018/978-1-60566-042-4.ch008
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Abstract

Composite applications leveraging the functionalities offered by Web services are today the underpinnings of enterprise computing. However, current Web services composition systems make use of only functional requirements in the selection process of component Web services while transactional consistency is a crucial parameter of most business applications. The transactional challenges raised by the composition of Web services are twofold: integrating relaxed atomicity constraints at both design and composition time and coping with the dynamicity introduced by the service-oriented computing paradigm. In this chapter, we present a new procedure towards automating the composition of transactional Web services. This composition procedure does not take into account functional requirements only but also transactional ones based on the acceptable termination states model. The resulting composite Web service is compliant with the consistency requirements expressed by business application designers and its execution can easily be coordinated using the coordination rules provided as an outcome of our approach. An implementation of our theoretical results based on OWL-S and business process execution language (BPEL) technologies is further detailed as a proof of concept.
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Introduction

Web services composition has been gaining momentum over the last years as it leverages the capabilities of simple operations to offer value-added services. These complex services such as airline booking systems result from interactions between Web services that can span over organizational boundaries. Considering the lack of reliability akin to distributed environments, assuring data and transactional consistency of the outcome of cross-organizational workflow-based applications, such as composite applications, is necessary. The requirements that are relevant to assuring consistency within the execution of Web services composite applications are mainly twofold:

  • Relaxed atomicity: atomicity of the execution can be relaxed as intermediate results produced by a workflow-based application may be kept despite the failure of a service. The specification process of transactional requirements associated with workflows has to be flexible enough to support coordination scenarios more complex than the coordination rule “all or nothing” specified within the two phase commit protocol (ISO, n.d.).

  • Dynamic assignment of business partners: composite applications are dynamic in that the workflow partners or component services offering different characteristics can be assigned to tasks depending on the resources available at runtime. Business partners’ characteristics have thus to be combined or composed in a way such that the transactional requirements specified for the workflow are met.

Existing transactional protocols (Elmagarmid, 1992), (Greenfield, Fekete et al. 2003) are not adapted to meet these two requirements as they do not offer sufficient flexibility to cope for instance with the runtime assignment of computational tasks. In addition, existing solutions to combine or compose service providers based on the characteristics they offer appear to be limited when it comes to integrating at the composition phase the consistency requirements defined by workflow designers. These solutions indeed only offer means to validate transactional requirements once the workflow business partners have been selected but no solution to integrate these requirements as part of the composite application building process. The next sections present our approach to overcome these limitations.

Chapter contributions

In this chapter, we present an adaptive transactional protocol to support the execution of composite applications. The execution of this protocol takes place in two phases. First, business partners are assigned to tasks using an algorithm whereby workflow partners are selected based on functional and transactional requirements. Given an abstract representation of a process wherein business partners are not yet assigned to workflow tasks, this algorithm enables the selection of service providers not only according to functional requirements but also based on transactional ones. In our approach, these transactional requirements are defined at the workflow design stage using the Acceptable Termination States (ATS) model. The resulting workflow instance is compliant with the defined consistency requirements and its execution can be easily coordinated as our algorithm also provides coordination rules. The workflow execution further proceeds through a coordination protocol that leverages the coordination rules computed as an outcome of the partner assignment procedure.

Chapter outline

The remainder of the chapter is organized as follows. Section 2 discusses related work and technical background. In section 3, we introduce preliminary definitions and the methodology underpinning our approach. A simple example of composite application is presented in section 4 for the purpose of illustrating our results throughout the chapter. Section 5 introduces a detailed description of the transactional model used to represent the characteristics offered by business partners. In section 6, we provide details on the termination states of a workflow then section 7 describes how transactional requirements expressed by means of the ATS model are derived from the inherent properties of termination states. Section 8 presents the transaction-aware service assignment procedure and the associated coordination protocol. An implementation of our theoretical results based on Web services technologies including OWL-S (OWL Services Coalition, 2003) and BPEL (Thatte, 2003) is presented in section 9. Finally, section 10 presents concluding remarks.

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Table of Contents
Foreword
Torbjørn Skramstad
Preface
Khaled M. Khan
Acknowledgment
Khaled M. Khan
Chapter 1
Ghita Kouadri Mostefaoui
The ultimate effectiveness in terms of quality achievements should be a key concern of systems built from Web services. To this end, in this chapter... Sample PDF
The Development, Testing, and Deployment of a Web Services Infrastructure for Distributed Healthcare Delivery, Research, and Training
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Chapter 2
Abdelghani Benharref, Mohamed Adel Serhani, Mohamed Salem, Rachida Dssouli
Web services are a new breed of applications that endorse large support from main vendors from industry as well as academia. As the Web services... Sample PDF
Multi-Tier Framework for Management of Web Services' Quality
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Chapter 3
Krishna Ratakonda
In this chapter we present an overview of research and development efforts across several different technical communities aimed at enabling... Sample PDF
Quality Models for Multimedia Delivery in a Services Oriented Architecture
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Chapter 4
Julio Fernández Vilas
Several open issues in Web services architecture are being solved by using different kinds of solutions. Standard high-availability techniques based... Sample PDF
Virtual Web Services: Extension Architecture to Alleviate Open Problems in Web Services Technology
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Chapter 5
Witold Abramowicz
The following chapter focuses on the problem of the proper definition of non-functional properties and methods that may be applied in order to... Sample PDF
Profiling of Web Services to Measure and Verify their Non-Functional Properties
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Chapter 6
Kyriakos Kritikos
As the Web service (WS) paradigm gains popularity for its promise to transform the way business is conducted, the number of deployed WSs grows with... Sample PDF
Enhancing the Web Service Description and Discovery Processes with QoS
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Chapter 7
Michael C. Jaeger, Matthias Werner
This chapter presents the definition of relevant terminology and a conceptual model of the basic terms. The chapter starts with the presentation of... Sample PDF
Web Services Dependability
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Chapter 8
Frederic Montagut, Refik Molva, Silvan Tecumseh Golega
Composite applications leveraging the functionalities offered by Web services are today the underpinnings of enterprise computing. However, current... Sample PDF
Transactional Composite Applications
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Chapter 9
Enrico Pontelli, Tran Cao Son, Chitta Baral
This chapter presents a comprehensive logic programming framework designed to support intelligent composition of Web services. The underlying model... Sample PDF
A Logic Programming Based Framework for Intelligent Web Service Composition
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Chapter 10
Daniel Brenner, Barbara Paech, Matthias Merdes, Rainer Malaka
For the foreseeable future, testing will remain the mainstay of software quality assurance and measurement in all areas of software development... Sample PDF
Enhancing the Testability of Web Services
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Chapter 11
Ghita Kouadri Mostefaoui, Zakaria Maamar, Nanjangud C. Narendra
This chapter presents our research initiative known as aspect-oriented framework for Web services (AoF4WS). This initiative looks into the role of... Sample PDF
Aspect-Oriented Framework for Web Services (AoF4WS): Introduction and Two Example Case Studies
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Chapter 12
Ty Mey Eap, Marek Hatala, Dragan Gaševic, Nima Kaviani, Ratko Spasojevic
The lack of intrinsic and user control in the identity management of today Internet security hampers the research in the area of Semantic Web and... Sample PDF
Open Security Framework for Unleashing Semantic Web Services
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Chapter 13
Vishal Dwivedi
This chapter underlines the importance of security service level agreements (SLAs) for Web services. As Web services are increasingly incorporated... Sample PDF
Providing Web Services Security SLA Guarantees: Issues and Approaches
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Chapter 14
Fatih Oguz
This chapter describes a research study with an objective to explore and describe decision factors related to technology adoption. The study... Sample PDF
Adoption of Web Services in Digital Libraries: An Exploratory Study
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Chapter 15
Bijoy Majumdar
Change is the only constant, and this concept holds good for services too. Service maintenance is the most tedious and longest phase of service... Sample PDF
Service Evolution and Maintainability
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Chapter 16
Pauline Ratnasingam
This chapter aims to examine the extent of Web services usage and quality, applying the balanced scorecard methodology in a small business firm as... Sample PDF
The Role of Web Services: A Balance Scorecard Perspective
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